Method of deforming and straightening a curved continuous casting strand

ABSTRACT

An arc type continuous casting plant for curved strands is comprised of adjustably positionable forming rolls and a straightening machine. The straightening machine is formed of a flexibly mounted holddown roll for applying variable pressure to the strands during the straightening operation, and, preferably, includes a counter roll disposed on the opposite side of the cast strand from the holddown roll. A hydraulic piston assembly may be used to mount the holddown roll for variable pressure operation. Further, the counter roll may be interconnected and movable relative to the holddown roll for handling strands of different thickness. In an embodiment with the strand oriented horizontally the holddown roll is positioned between two pairs of forming rolls while in an arrangement with the strand positioned vertically, the forming rolls are disposed between spaced holddown or straightening rolls.

United States Patent [72] lnventm' C Hermann; 3,491,823 1/1970 Tarmann et al 164/76 Hans G- aum Duisburg, Germany 3,491,824 1 /1970 Tarmann et al 164/76 5; 2 1969 1 Primary Examiner-J. Spencer Overholser 1 l e v Assistant Examiner-R. Spencer Annear lvision of Ser. No. 678,391, Oct 26 1967 Attorney-Mo Glew and Toren [45] Patented Jan. 12,1971 [73] Assignee Demag Aktiengesellschaft Duisburg, Germany [32] Priority Nov. 10, 1966 [33] Germany pslsos ABSTRACT: An arc type continuous casting plant for curved I strands is comprised of adjustably positionable forming rolls [54] METHOD OF DEFORMING AND STRAIGHTENING and a straightening machine. The straightening machine is A CURVE], CONTINUOUS CASTING STRAND formed of a flexibly mounted holddown roll for applying varia- 3 Chums 1 Drawing ble pressure to the strands during the straightening operation, and, preferably, includes a counter roll disposed on the op- 164/82 posite side of the cast strand from the holddown roll. A

164/ 76 hydraulic piston assembly may be used to mount the hold- 822d 11/12 down roll for variable pressure operation. Further, the counter [50] FlQld ofSearch 164/76, 82, n may be interconnected and movable relative to the hold 1 v 270, 273, 282, 283; 72/ I61, 1 down roll for handling strands of different thickness. In an embodiment with the strand oriented horizontally the holddown [56] References cued roll is positioned between two pairs of forming rolls while in an UNITED STATES PATENTS arrangement with the strand positioned vertically, the forming 648,091 4/1900 Trotz rolls are disposed between spaced holddown or straightening 3,3 14,1 l5 4/1967 Saunders et al rolls.

PATENTEUJANQIB?! 3554.269

INVENTORS Curt Herrmonn Hons G. Buumonn ATTORNEYS METHOD OF DEFORMING AND STRAIGHTENING A CURVED CONTINUOUS CASTING STRAND This is a division of application Ser. No. 678,391, filed Oct. 26, 1967.

SUMMARY OF THE INVENTION.

The present inventionis .directed to an'arc type continuous casting plant, especiallyfor casting steel, andmore particularly, to an arrangement wherein one or more pairs of adjustably positionable forming rolls are disposed adjacent to a withdrawing and straightening machine'ln arc type continuous casting plants, straightening machine, have been employed to straighten the casting or strand-usually a bar shape, after it has been given -a curved-configurationin the casting operation. Although the shellof the casting has a certain thickness at the place. where it is straightened, it is possible, without anymajor: cracksor ruptures in the strand, to bring about the requiredchange indirection. I

However, ifinstead of a-straighteningrnachine, a device using rolls is employed for bringingabouta deformation or a reduction in the cross section of the casting, then quite a different condition exists. With the change in the shape of the strand an increasinglength of the path of travel of the casting is developed and it tends to retainits curved form because of the increasing cooling time-which is provided. This tendency of the casting to cool and retain itscurved' form is also due, in part, to the fact that the forming-rolls must be made adjustableto permit the leading end of the strandto. extend through them 'at the beginning of the casting operation; As the strand passes through the forming rolls, it experiences'a change in form-relative toits cross section. However, it does not change its curved formas it would if it hadbeen passed through a; straightening machine.

if the. forming rolls are arranged adjacent to the device where the curved strand is straightened,-problems, which have not previously been. appreciated,v could develop andlead to cracks and even fracturesin the casting which would result in the interruptionzof the entire operation. Where such interruptions occur, the product of theioperation is useless and serious economiclosses result. 7 Q

Because of the arrangement of'thedeforming rolls, whether the casting' is oriented. horizontally or vertically, there results an arching of the strand which causes the cast member to retain its curved shape..At the commencement of the':casting operation, the leading end of the strand must be passed through the first pair of rollers since any deformation at the end of the strip may resultin the complete destructionof the casting. in such plants, the strand isxnot guided into. the

straightening machine sothatit isnot possible to obtain a usa-' ble product.

Accordingly,.one of the primary objects of the presentinvention is to overcome thisdrawback in initiating the deforrn-. ing and straightening operation and, in particular, to-prevent '55 any archingof the strand after its passage between the first forming rollers to preventthe tendency of the strand to retain rolls fonning the strand. The holddown rolls are provided against the upperside of the strand when thestrand is arranged horizontally, and are flexible within certain limits-in.

theextent to whichpressurecan be applied to the strand. This arrangement is not merely intended to support the strand as it is being deformed, but-rather, in accordance with the condi tions of the strand passing through the rolls to press the strand uniformly against the baseof the holddown or straighteningdevice whereby the strand is reoriented into a straightline and any arching. stresses which existed within the strand arev eliminated.

Accordingly,.the present invention has the advantage of straightening'the strand immediatelyafter the deforming operation while it is ina state where this can be done. it has the further advantage of eliminating, at least to a degree. the inherent stresses which are developed in the strand.

in one embodiment of the invention, where the rolls are mounted in a vertically arranged frame, it is preferred to dispose the holddown rolls between a spaced pair of forming rolls in the frame. Such anarrangem'ent has the advantage of providing an almost equilateral change in form and direction of the cross section of the strand and of its axis.

On the other hand, if the frame supporting the rolls is disposed horizontally, it has been found advantageous to dispose the holddown rolls on either side of the forming rolls. in this arrangement, the deformation of the strand takes place between two points of support for the strip and, as a'result, not only may a precise pass through the forming rolls be achieved, but also in this combination a complete change in the orientation of the strand from a curved to a straight line disposition is obtained.

Based on the given conditions of the dimension of the strand and the data of the continuous casting operation, it is possible to determine the specific transition point for locating the holddown roll for changing the shape of the strand from curved to straight. In such a setup the deforming means can be positioned either in front of or behind the point at which the strand is straightened.

Moreover, in accordance with the invention, the holddown rolls may be flexibly supported by means of hydraulic pressure regulation equipment. In this arrangement, a smaller or greater force can be exerted on the strand depending on the particular conditions of the strand as it passes through the straightening device.

Another featureof the invention is that the holddown roll need nothave the profileor shaped the cast member such as is required of adeforrning or reducing roll, because, at the point where the holddown roll is positioned, the strand does not experience-any deformation, or thedeforrnation is of a relatively small amount in comparison to that provided by the deforming rolls. To assure the proper application of pressure,

by means of the holddown roll, a hydraulic device is particularly suitable because it provides a range of pressure forcesand also permits fine adjustment of the application of pressure to the holddown roll.

Still, another feature of the invention is that the flexible sup- .port for the holddown may be provided by a pressure spring support with a steep curve in its force displacement characteristic. In simple arrangements such a support device can effectively provide a flexible influence on the strand.

In the straightening operation, in addition to the'holddo'wn roll one or a number of counter rolls may be positioned on an opposite side. of the strand from the holddown roll. The counter roll is preferably associated with the holddown'roll in such a manner that the counter roll ismovable relative to the holddown roll permitting a variation in the dirrrension-ofrthe strands which may be passed between them.'The-feature of varying the spacing between the holddown and' counterarolls is of particular importance because the casting passing; from the forming rolls to the straightening device may be of varying" dimensions. Additionally, this variable arrangementot". therolls has a further advantage in guiding the leading end of' the strand at'the beginningof the casting operation-sinceit is cooled ofl to a greater degree than the portion-which follows it. At the beginning of the casting operation as the forming": rolls are adjusted the holddown and counter rolls-are'abletofollow the changes in the dimensions of the strand -as=it istfedinto the straightening device.

The variousfeatures of novelty which characterize the in1-' vention are pointed out with particularity in the claimsannexed to and forminga part of this specification. Fora better understanding of the invention, its operating advantagesandspecific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter'in which there is illustrated and described a preferred embodiment" of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings In the drawing, a vertical sectional view is shown of a diagrammatic arrangement of an arc type continuous casting plant with the casting being passed between the forming and straightening means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, a strand 1 in an arc type continuous casting operation is shown passing through a machine frame 2 which contains two deforming or shaping stations 3 and 4. The deforming station 3 contains a pair of horizontally arranged adjustably positionable rolls 5 and 6 which are located at a relatively short distance from a pair of vertically disposed rolls 7 in the other deforming station 4. As can be noted in the drawing, the section lb of the strand 1 as it enters the gap between the rolls 5 and 6 is reduced or compressed in a vertical direction and as it passes between the rolls 7, it is deformed in the horizontal direction providing the deformed strand section la.

Located between the two pairs of rolls 5 and 6, 7 is a straightening device comprising an upper holddown roll 8 and a lower counter roll 9. The counter roll 9 may be held rigidly in position or, as previously mentioned, it may be adjustable relative to the holddown roll 8 by means of the hydraulic control for the holddown roll.

The holddown roll 8 is supported by a fork member 10 secured to the roller bearings of the holddown roll. The fork is, in turn, articulated to the piston rod 11 which forms a portion of the piston driving mechanism 12. The piston drive mechanism 12 is flexibly mounted on the frame 2 by means of a connection 13.

The arrangement set forth in the drawing operates in the following manner. At the beginning of the continuous casting operation, the leading edge of the strand or casting is passed between the adjustably positionable rolls 5 and 6 which are spaced apart for admitting the leading edge between the holddown roll 8 and its counter roll 9. The rolls 8 and 9 which perform the straightening operation do not cause any appreciable deformation of the cross section of the strand. With the leading edge of the strand guided into the straightening rolls, the forming rolls 5 and 6 are positioned against the strand and the operation is ready to commence. By means of a control system (not shown) the rolls 8 and 9, which may be adjusted either automatically or manually, are now ready to perform the straightening operation on the strand emerging from between the rolls 5 and 6. As the straightened strand passed from the rolls 8 and 9 to the vertically arranged rolls 7, it is almost completely freed from internal stresses caused by its curved orientation prior to entering the rolls 5 and 6. The speed of the continuous casting operating and of the rolling and straightening steps is adjusted relative to one another so that the circumferential speed of the forming rolls take into account fully the degree of deformation being impressed on the strand. Ac cordingly, depending on the cross-sectional dimensions of the strand, the section In of the strip emerging from the vertical rolls 7 can have a speed in its path of travel which is a multiple of that of section 1b of the strip which is delivered into the horizontally arranged rolls 5 and 6.

The driving mechanism for the horizontally and vertically arranged rolls 5 and 6 and 7 may be located either below the level of the casting room floor 14 or mounted on the side of the frame 2.

While the holddown roll 8 and the counter roll 9 perform the straightening operation by themselves it is possible that they may be supported in this operation by the deforming rolls. The tendency of the curved strand to arch in one direction or another is primarily a function of the manner in which the roll dimensions in the deformin stations 3 and 4 are arranged. For example, by means of a sm ler lower roll in the deforming station 3, the downward pressure or force of the holddown roll 8 can be supported whereby with a pinion means and a smaller circumferential speed of the lower roll a larger frictional force can be transmitted to the under side of the strand when it is desired to provide a greater downward force on the casting. Accordingly, the holddown and counter rolls not only effectively straighten the strand but also, in combination with one or both of the deforming stations, can influence the internal stresses of the strand. It is also within the scope of the invention in the event that several holddown rolls are employed to provide counter rolls on either the upper or lower side of the strand in a staggered arrangement.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

We claim:

1. A method of straightening a casting in an arc type continuous casting plant comprising the steps of passing the casting continuously along a curved path of travel, deforming the casting as it moves along its path of travel, and adjustably applying pressure to the casting adjacent to said deformation for straightening the strand and freeing it of internal stresses caused by its curvature prior to deformation.

2. A method as set forth in claim 1 comprising the step of arranging the straightening of the casting between a location where the casting is vertically deformed and one where it is horizontally deformed.

3. A method as set forth in claim 2 comprising the step of passing the leading edge of the casting through the location of the deforming step without deforming the casting and after the leading edge is engaged in the straightening step commencing to deform the casting. 

1. A method of straightening a casting in an arc type continuous casting plant comprising the steps of passing the casting continuously along a curved path of travel, deforming the casting as it moves along its path of travel, and adjustably applying pressure to the casting adjacent to said deformation for straightening the strand and freeing it of internal stresses caused by its curvature prior to deformation.
 2. A method as set forth in claim 1 comprising the step of arranging the straightening of the casting between a location where the casting is vertically deformed and one where it is horizontally deformed.
 3. A method as set forth in claim 2 comprising the step of passing the leading edge of the casting through the location of the deforming step without deforming the casting and after the leading edge is engaged in the straightening step commencing to deform the casting. 